Birmingham, AL—Could a commonly-used calcium channel blocker be used to help treat diabetes?

A study published recently in the journal Diabetes Research and Clinical Practice reports an association between verapamil use and lower fasting glucose levels in humans with diabetes.

For the study, researchers examined the association of calcium channel blockers and verapamil use with fasting serum glucose among nearly 5,000 adult diabetes patients participating in the REGARDS (Reasons for Geographic and Racial Differences in Stroke) project, which was sponsored by the National Institutes of Health to learn more about factors leading to cardiovascular disease.

Of the participants, 1,484 used calcium channel blockers (174 of them were on verapamil), widely used to treat high blood pressure, irregular heartbeat, and migraine headaches. Results indicate that calcium channel blocker users had 5 mg/dL lower serum glucose compared to nonusers, while uses of verapamil specifically had, on average, 10 mg/dL lower serum glucose compared to those not taking calcium channel blockers at all.

At the same time, verapamil users who took insulin in combination with oral medication had a 24 mg/dL lower serum glucose, and verapamil users who took insulin alone to manage their diabetes showed a 37 mg/dL lower serum glucose, according to the results.

“This is a cross-sectional observational study unlike the current prospective randomized UAB verapamil clinical trial, so we can't infer causal relationship between using verapamil and lower glucose levels; but we can say there is an association with lower glucose levels, and that is absolutely encouraging,” said lead author Yulia Khodneva MD, PhD.

Findings in the final subgroup, which used insulin alone and included participants who had mostly Type 1 or severe Type 2 diabetes, also were notable, according to the researchers.

“The change in glucose for that group compared to those not taking verapamil—37 mg/dL—is almost four times higher than when you look at the whole sample of diabetic adults," Khodneva added in a UAB press release. “That made us think that verapamil is predominantly active for participants who have Type 1 diabetes or those with Type 2 diabetes who have really damaged beta cells. There seems to be something that works on the structural level, especially for those who have stronger beta-cell damage.”

Principal investigator Anath Shalev, MD, director of UAB’s Comprehensive Diabetes Center, pointed out that the difference is equivalent to about a 1% reduction in hemoglobin A1c.

Research at UAB has uncovered how high glucose levels lead to overproduction of a protein called TXNIP, which can kill pancreatic beta cells and reduce insulin production. Previous mouse studies there have shown that verapamil can lower TXNIP levels by decreasing calcium concentration in the beta cells and potentially eradicate diabetes.

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